scholarly journals Log D Analysis Using Dynamic Approach

2018 ◽  
Author(s):  
Ganesh Kumar Paul ◽  
Prashanth Alluvada ◽  
Esayas Alemayehu ◽  
M.S. Shahul Hameed ◽  
Wasihun Alemayehu ◽  
...  
Keyword(s):  
Distribution Coefficient ◽  
Nalidixic Acid ◽  
Organic Phase ◽  
Algebraic Method ◽  
Pharmaceutical Formulations ◽  
Dynamic Approach ◽  
Ionic State ◽  
Lipinski’S Rule ◽  
Aqueous Buffer ◽  
Amphoteric Molecules

ABSTRACTLog D is one of the important parameters used in Lipinski’s rule to assess the druggability of a molecule in pharmaceutical formulations. It represents the logarithm (log10) of the distribution coefficient (D) of a molecule. The distribution coefficient is defined as the ratio of the concentration of the sum of ionized and unionized species of a molecule distributed between a hydrophobic organic phase and an aqueous buffer phase. Since the pH affects the ionic state of a molecule, log D value (which is dependent on the concentrations of the ionized species) also becomes dependent on pH. In this work, the conventional algebraic method is compared with a more generalized ‘dynamic’ approach to model the distribution coefficient of amphoteric, diamino-monoprotic molecule and monoprotic acid in the presence of salt or co-solvent. Recently reported experimental log D data of amphoteric molecules such as nalidixic acid, mebendazole, benazepril and telmisartan, were analyzed using both these approaches to show their equivalence.GRAPHICAL ABSTRACT

The partition separation of tropane alkaloids

1954 ◽  
Vol 7 (2) ◽  
pp. 189 ◽  
Author(s):  
W Botttomley ◽  
PI Mortimer
Keyword(s):  
Distribution Coefficient ◽  
Organic Phase ◽  
Tropane Alkaloids ◽  
Partition Chromatography ◽  
Aqueous Buffer ◽  
Chromatography Column ◽  
True Distribution

Data on the partition of tropane alkaloids between an aqueous buffer phase, of varied pH, and chloroform are presented in terms of the pH at which 50 per cent. extraction occurs. The true distribution coefficient of some of the alkaloids is derived from the data. The effect of varying the organic phase has been studied. From the data obtained, the operation of an analytical partition chromatography column is described.

scholarly journals Extraction Recovery of Vanadium(V) by Amines

2020 ◽  
Author(s):  
Lyudmila D. Kurbatova ◽  
Olga V. Koryakova ◽  
Marina S. Valova
Keyword(s):  
Infrared Spectroscopy ◽  
Distribution Coefficient ◽  
Organic Phase ◽  
Distribution Coefficients ◽  
Extraction Recovery ◽  
Medium Concentration ◽  
Solvent Type

The extraction of vanadium (V) by N-(2-hydroxy-5-nonylbenzyl)-β, β- dihydroxyethylamine was studied depending on different factors, such as pH of the medium, concentration of extracting agent, temperature and solvent type. This allowed the optimal extraction conditions to be determined. It was shown that extraction of vanadium (V) takes place with high distribution coefficients, and a complex containing a decavanadate anion and four molecules of the extractant is formed in the organic phase. The extracted vanadium (V) complex with amine is stable for more than one month. Keywords: extraction, vanadium, distribution coefficient, infrared spectroscopy

Extraction of Technetium as [Tc(II)(NO)(AHA)2H2O]+ Species in the UREX Process

2009 ◽  
Author(s):  
Patricia Paviet-Hartmann ◽  
Ana Nunez Gomez-Aleixandre ◽  
Joshua Pak ◽  
Amparo Glez Espartero ◽  
Frederic Poineau ◽  
...  
Keyword(s):  
Phase Composition ◽  
Nitric Acid ◽  
Distribution Coefficient ◽  
Recent Work ◽  
Crown Ethers ◽  
Organic Phase ◽  
Dielectric Constants ◽  
Acetohydroxamic Acid ◽  
Ring Size ◽  
Reductive Nitrosylation

As it is envisioned today, the first segment of the UREX+ process uses low nitric acid concentrations for U(VI) extraction where pertechnetate anion, TcO4−, can be co-extracted with the uranyl and nitrate into TBP-hydrocarbon solutions. A reductant complexant, acetohydroxamic acid (AHA) is added to the process through the scrub to limit the extractability of plutonium and neptunium. Recent work performed in our laboratory (Ref. 1) demonstrated that TcO4− undergoes reductive nitrosylation by AHA under a variety of conditions. The resulting divalent technetium is complexed by AHA to form the pseudo-octahedral trans-aquonitrosyl-(diacetohydroxamic)-technetium(II) complex ([Tc(II)(NO)(AHA)2H2O]+). In this paper, we are reporting the extraction of [Tc(II)(NO)(AHA)2H2O]+ complex by new designed macrocompounds as well as commercially available crown ethers from 18-crown-6 to 24-crown-8 in ring size and of varying derivatization. Several organic diluents with different dielectric constants are used to enhance the distribution coefficient of technetium (II). The experimental efforts are focused on determining the best extraction conditions by varying the macrocomponds nature and concentration, and the organic phase composition.

The Iodine Propanenitrile Water-System. Effects of Added Salts on Distribution Coefficient and Conductivity

1987 ◽  
Vol 40 (1) ◽  
pp. 209
Author(s):  
J Avraamides
Keyword(s):  
Distribution Coefficient ◽  
Organic Phase ◽  
Water System ◽  
Solvent System ◽  
Distribution Coefficients ◽  
Metal Halides ◽  
Two Phase ◽  
Water Solvent ◽  
Positive Effect ◽  
Zinc Iodide

Distribution coefficients for iodine in the propanenitrile-water solvent system were measured as a function of the nature and concentration of various added metal halides. BothNaCl and KI at concentrations between 1 and 3 M had a positive effect on the distribution coefficient. Zinc halides, particularly zinc iodide, tended to lower the distribution coefficient significantly and also raised the conductivity of the organic phase. These studies suggest that the two-phase solvent system is suitable for application in a zinc-iodine battery.

Review of Psychotherapy: A Dynamic Approach. 2nd ed.

1972 ◽  
Vol 17 (2) ◽  
pp. 79-79
Author(s):  
JAMES BIERI
Keyword(s):  
Dynamic Approach

Language, Aging, and Culture: A Dynamic Approach

PsycCRITIQUES ◽  
2006 ◽  
Vol 51 (22) ◽  
Author(s):  
Francine Conway ◽  
Nina Finkel
Keyword(s):  
Dynamic Approach

An algebraic method for solving Hartree-Fock-Roothaan equations

1990 ◽  
Vol 87 ◽  
pp. 2017-2025 ◽  
Author(s):  
Lac Malbouisson ◽  
JDM Vianna
Keyword(s):  
Algebraic Method ◽  
Hartree Fock

ANTIMICROBIAL SUSCEPTIBILITY IN CULTURE POSITIVE ENTERIC FEVER

2019 ◽  
Vol 3 (7) ◽  
Author(s):  
Dr. Manish Kulshrestha ◽  
Dr. Anjali Kulshrestha
Keyword(s):  
Bone Marrow ◽  
Blood Culture ◽  
Nalidixic Acid ◽  
Antimicrobial Susceptibility ◽  
Salmonella Enterica ◽  
Enteric Fever ◽  
Multidrug Resistant ◽  
Bone Marrow Culture ◽  
Diffusion Method ◽  
Culture Positive

INTRODUCTION: Enteric fever includes typhoid and paratyphoid fever. Peak incidence is seen in children 5–15 years of age; but in regions where the disease is highly endemic, as in India, children younger than 5 years of age may have the highest infection rates. There are about 22 million new typhoid cases occur each year. Young children in poor, resource limited areas, who make up the majority of the new cases and there is a mortality figures of 215,000 deaths annually. A sharp decline in the rates of complications and mortality due to typhoid fever is observed as a result of introduction of effective antibiotic therapy since 1950s. MDR-ST became endemic in many areas of Asia, including India soon after multidrug-resistant strains of Salmonella enterica serotype typhi (MDR-ST) that were resistant to all the three first-line drugs then in use, namely chloramphenicol, amoxycillin and co-trimoxazole emerged in early 1990s. MATERIAL AND METHODS: Only blood culture or bone marrow culture positive cases were included. The patients with culture isolated enteric fever were included in the study. Antimicrobial susceptibility testing was carried out by disk diffusion method using antibiotic discs. The analysis of the antimicrobial susceptibility was carried out as per CLSI interpretative guidelines. RESULTS: A total of 82 culture positive cases were included in the present study. 80 culture isolates were from blood culture and 2 from the bone marrow culture. Salmonella entericasubspecies enterica serovartyphi (S typhi) was isolated from 67 (81.70%) patients while Salmonella enterica subspecies entericaserovarparatyphi (S paratyphi A) was isolated from 13 (15.85%) cases and 2 (2.44%) were Salmonella enterica subspecies entericaserovarschottmuelleri (S paratyphi B). Of the 82 cases 65(79.3%) isolates were resistant to ciprofloxacin, 17 (20.7%) were resistant to nalidixic acid, one (1.2%) case each was resistant to Cefotaxime and ceftriaxone, 2 (2.4%) were resistant to chloramphenicol, 10 (12.2%) were resistant and to cotrimoxazole 3 (3.7%) were resistant. CONCLUSION: In a culture positive cases 65(79.3%) isolates were resistant to ciprofloxacin and 17 (20.7%) were resistant to nalidixic acid. Multidrug resistant isolates were 65(79.3%).

Development of Validated Stability Indicating HPTLC Method for Assay of Ozagrel and its Pharmaceutical Formulations

2018 ◽  
pp. 36-48 ◽  
Author(s):  
Vishal N Kushare ◽  
Sachin S Kushare
Keyword(s):  
High Performance ◽  
Linear Regression Analysis ◽  
Pharmaceutical Formulations ◽  
Base Hydrolysis ◽  
Assay Method ◽  
Related Substance ◽  
Stability Indicating ◽  
Regular Production ◽  
Hptlc Method

The present paper describes stability indicating high-performance thin-layer chromatography (HPTLC) assay method for Ozagrel in bulk drugs. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of toluene: methanol: triethylamine (6.5: 4.0: 0.1 v/v/v). The system was found to give compact spot for Ozagrel (Rf value of 0.40 ± 0.010). Densitometric analysis of Ozagrel was carried out in the absorbance mode at 280 nm. The linear regression analysis data for the calibration plots showed good linear relationship with r2 = 0.999 with respect to peak area in the concentration range 30 - 120 ng/spot. The developed HPTLC method was validated with respect to accuracy, precision, recovery and robustness. Also to determine related substance and assay determination of Ozagrel that can be used to evaluate the quality of regular production samples. The developed method can also be conveniently used for the assay determination of Ozagrel in pharmaceutical formulations. The limits of detection and quantitation were 4.069 and 12.332 ng/spot, respectively by height. Ozagrel was subjected to acid and alkali hydrolysis, oxidation, photochemical and thermal degradation. The drug undergoes degradation under acidic, basic, oxidation and heat conditions. This indicates that the drug is susceptible to acid, base hydrolysis, oxidation and heat. Statistical analysis proves that the method is repeatable, selective and accurate for the estimation of said drug. The proposed developed HPTLC method can be applied for identification and quantitative determination of Ozagrel in bulk drug and tablet formulation.

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